Stirling Second Kind Count

Problem

The Stirling number of the second kind S(n, k) counts partitions of n labeled items into k nonempty unlabeled blocks, via S(n, k) = k S(n-1, k) + S(n-1, k-1).

Given n and k, return S(n, k).

Hint

Either join one of the existing blocks or start a new block.

Test cases

case 1

in: [4,2]

expected: 7

case 2

in: [5,3]

expected: 25

case 3

in: [3,3]

expected: 1

Starter codePython

def stirling_second_kind_count(n, k):
    # Your code here
    pass

3 test cases · run your code against them in the editor